Diffraction and polarisation Unpolarised Plane polarised Partially polarised Describe what is meant simply by the term ‘polarised’ or ‘polarising’ Differentiate between ‘plane polarised’ and ‘partial polarisation’ Explain why sound waves cannot be polarised but light waves can

Polarisation “restricting the vibrations of a transverse wave wholly or partially to a specific direction” An unpolarised light source (e.g. bulb/sun) will emit light in lots of different planes However we are able to use filters to restrict these planes (i.e. block some planes and let others through!) What would you observe once a second filter that was set horizontally was placed after the first filter? Delta

Have a try! π/2 Here we have two polarising filters placed perpendicular to one another Notice how as you rotate on the of the filters, the intensity of light that is let through changes. When is the intensity at it’s maximum and why? Delta When is the intensity at it’s minimum and why?

Plane Vs Partial When light reflects off a surface, it will experience partial polarisation. Here, the light is not restricted to a single plane but often only the horizontal planes get reflected Delta

Polarising Sunglasses